In the use of liquid carbon dioxide for injection with various liquid well treating materials, it has been necessary in the past to use two high-pressure pumps; one for the injection of an aqueous or hydrocarbon-based liquid stream and one for the liquid carbon dioxide stream to achieve the required injection and mixing pressures.
These high-pressure pumps, which are large pumps, are typically mounted on heavy duty trucks for movement to a well area. These pumps are typically massive, positive displacement pumps having one or multiple plungers and are used to increase the pressure of injection streams to a pressure suitable for injection into a well up to and at or exceeding fracturing conditions as required. The use of these pumps is expensive since they are subject to a substantial per diem charge as a result of the high cost of the pumps and because such pumps have relatively high maintenance costs.
Accordingly, a more efficient and economical way to inject a stream of liquid carbon dioxide and a liquid stream of aqueous or hydrocarbon-based liquid treating solution into a well at a suitable pressure has been sought.